This is a continuing investigation of the factors controlling survival of pathogenic bacteria and certain fungi on human skin. We demonstrated that certain pathogenic bacteria and Candida albicans, when deposited on human skin and partially occluded, are significantly reduced in number or even eliminated. We further observed that the antimicrobial activity of skin varies from individual to individual; some subjects tend to destroy these applied bacteria while others do not. This antimicrobial property of skin is effective against Staphylococcus aureus and Candida albicans. Skin lipids have been considered antimicrobial by some authors. We have delineated populations of men in terms of persistence or inhibition of S. aureus applied to their skin. The normal flora of these polar-type populations will be quantified. It will be determined whether these individuals tend to be at the high or low ends of a distribution curve in terms of the number and types of their normal skin flora. We will correlate the presence of antimicrobial skin lipids with the absence of pathogenic bacteria. Skin lipids will be extracted with acetone and fractionated. Both quantitative and qualitative analyses of skin lipids in terms of antimicrobial activity will be performed. Different fractions of lipid will be tested for their ability to prevent multiplication of microorganisms. These fractions will be characterized chemically. The isolation and successful identification of these fractions will be useful in investigating the effectiveness of these antimicrobial agents in the prevention of skin infection.